Mechanical relay



A. BARR ET Al.

MECHANICAL RELAY Nov. 17, 1925; 1,362,279

Filed Sept. 1, 1922 3 Sheets-Sheet 1 NOV. 17,1925; i

A. BARR ET AL MECHANICAL RELAY Filed Sept. 1, 1922 3 Sheets-Sheet 2 Nov. 17', 1925- MECHANICAL RELAY Fi led Sept. 1, 1922 A. BARR 3 Sheets-Sheet 5 FIG-'6'.

U I l I a X .o A? H I L- I M 4 64 WM find,

Patented Nov. 17, 1925.

UNITED. STATES,

g 1,562,279, PATENT ARCHIBALD BARR AND WILLIAM s'rnoUn-or GLASGOW,'SCOTLA1\TD, AssrGNoRs -To.

BARR AND s'rnoun, LIMrrEn, 'orANNiEsLANn, GLASGOW, sco'rLA1vn. r

MECHANICAL RELAY."

Application filed September To all whom it may concern: Be it known that we, AROHIBALD BARR and l/VILLIAM SrRoUD, subjects of the King of Great Britain and Ireland, and both ofGaxton Street, Anniesland, Glasgow, Scotland, have invented new and useful Improvements in Mechanical Relays, of whichthe following is a specification. r v

This invention refers to mechanical relays of the type comprising a. servomotor for driving apparatus offering considerable 're-' sistance or having much inertia, so as to keep the apparatus in conformity with indications sent by a transmitter to a receiver say, by means of a step-by-step transmitter and receiver, said receiver being it self incapable of driving the apparatus.

The servomotor to be used may comprise any suitable type of motor (electric, hydraulic or other type), and for the purposes of this invention comprises a driven element and two driving elements, so arranged that with the motor in operation both driving elements may be allowed to run free,

in which case no motion is transmitted to g the driven element but when one of the drivingelements is stopped the other operates t transmit the drive, the motion thereby transmitted to the driven element being in one sense when the one drivingelement is stopped and in the opposite sense whenthe other is stopped. v

The apparatus to be drivenand kept in conformity comprises a differential gear of any suitable'type (bevel wheel, lever or other type), one element of which is moved inaccordance with indications of a receiver,

while a second element is actuated by the driven element of the servomotor, whereby motion is imparted to the third element of the differential gear by the receiver and motion in a counter sense is imparted tothe third element by the servomotor, so that the third element when displaced from a definite fiducial position by the action of the receiver is brought back toithat position by the action'of the servomotor. Thus the motion of the second element becomes a measureof the motion of the receiver.

This invention relates principally to the means for separately stopping the driving elements of the servomotor, and consists in the provision of control mechanism comprising a differential gear, to one element of which (the driving element) motion is representing another scroll, disc;

1, 1922. Serial at. 585,822.

' imparted" forwards or backwards the re d in curs only when theparts arei n the process of leaving or returning to the fiducial position. i. 'An example of mechanism and modifications according to this i'nvention will now be described with reference to the accompanying drawings, in which:-. i

Figure-l is a key diagram.

Figure 2 is a side elevation representing so a scroll disc associated with the control mechanism, Figure 3 1s a similar 'fview .Figure .4: is an elevation. illustrating a complete apparatus. Y v r p i I Figure 5 is an elevation and 6' isa plan of an apparatus more compactly arranged;

I Figure 7 is an elevation showing a modification of'the control'mechanism; i

In Figure 1, d designates a differential comprising bevel wheelse 7 6 andiD. adifferential gear comprising bevel gVVhQBlS E J E A receiver,isay a step-by step receiver, not shown, isarranged to rotate shaft Kto which lSj fiXQCl the spindleof planet wheelfj. 9 j

Thebevel wheel cis controlled by the servo motor' while bevel wheel 61 is' geared to planet wheel JV of'D, the spindle of J being fixedto shaft Ar F ixed-to bevel ,wheels E.

and E resepectively; are scrolldiscs F and F ,'F being represented'in Figure 2 and F in Figure 3. Two pins P andl f engage respectively in these scrolls, the two, pins move in unisonbeingfixed respectively to arms L and L connected ,to rock angularly 1 with a shaft carried by fixedbearings- The scroll disc F isconnected to turn angularly with arms H 11 constituting holders I Y which rockin unison, in such a manner that when pin P is in the ,position shown in .11 0

- Figure l2,'neither H nor H holds the servomotor. The servo'motor may be of any suitable type, for example, as follows :-C represents a shaft continuously driven in the appropriate direction by some form of motor not shown, and is the power shaft of the servomotor. Fixed to shaft C is the spindle of the bevel wheel 7 gearing with the bevel wheels 8 and 9. Toothed detent X and gear wheel 10 are connected to rotate with 8 and toothed detent Y and gearwheel 11 are connected to rotate with '9 (in Figure 4 the detents X and Y are carried by a shaft N and connected with 8 and 9 by gearing). Wheel-1O gears with wheel 12 and wheel 1'1 with 13 through an idle wheel 19. Bevel wheel 14'is'fixed to 12 and bevel wheel 16 to 13. 15 is a further bevel. wheel gearing with 14 and '16, the spindle of 15being connected torotate with shaft M. The three bevel wheels 14, 15 and 16 "thus form an ordinary differential gear.

Then both detents revolving in the same sense, the wheels 12 and 13 will berevolving in opposite directions, owing to the presence of the idle wheel '19. Under these conditions the spindle of bevel wheel 15 fixed to shaft M will have very little tendency to turn. If, however, detent X is stopped by holder H, shaft M will rotate in the same sense as the power driven shaft C whereas if Y is stopped by holder H the direction of rotation of M will be reversed. 'Fixed'to shaft M is a'toothed wheel 17 gearing with wheel 18 connected to rotate with wheel '6, so that, as M rotates, it drives bevel wheel J of the differential gear D by means of the parts 17 18 e j e in such a way as'to wipe'out'-the motion of J produced by the action of the receiver associated with K.

When then the receiver turns "shaft K the result willdependonthepositions of pin P (Figure 2-) and P (Figure 8). If P and P a re'nearer to the centres of their respective circlesthan thatshown in the figures,'wheel F will be locked by pin P while wheel F? willjbe'driven insu'ch' a direction as to increase the radialdistances of pins P and P If, however, P and P in the starting position are farther from the centres of their respective circles than that shown in the figures, wheel F will still be locked by pin and all the drive "will still be imparted to F as before',but the locked position of Fis (as will be seen from Figure 2) slightly "different when P is nearer'the centre than when it isfarther from the centre.

It will be seen then that under all circumstances F only turns through a very smallangle. Now the holders H and H which stop detents X and Y respectivelyare geared directly to wheel F and the position is such that when the radial distance of P is greater than that of the sloping groove X and Y are free and G (Figure 2), X, say, is stopped, while Y is stopped when this radial distance is less than that of G. The direction of rotation of the power driven shaft C issorelated to the other parts of the mechanism that the scroll disc F is always driven in such a direction that P (Figure 3) tends to move towards the stop S (Figure 3), thus e. g. if P .is nearer the centre than S the rotation is clockwise, while if P is farther from the centre than S the rotation is counter-clockwise.

When the receiver shaft K is quite out of step with the shaft M, the pin P (Figure 3) will not be at the stop S, but the scroll disc F will be angularly displaced with reference'to the positionof Figure 3, so that P will lie upon either the inner or outer part of the scroll. Thus, the angular distance between 'F and P is a measure of the amount the shafts K and M are out of step.

Under these conditions one or other of de- 1 tents X or Y is stoppedand shaft M is being driven in such a direction as to tend to bring it into conformity with the position of shaft K. As shaft M is being brought into conformity with K, wheel 17 drives F (through the intervention of the parts 17, 18, e je J E in such a direction as to bring P to the stop S. The position shown in Figures 2 and 3 thus corresponds to the position of conformity of shafts K and M the'fiducial position or the position of conformity. If now K moves one step forward, F being held by stop S, the drive *will'fall upon F (Figure 2) thus (by means of the sloping groove Gr) moving pin P nearer to or farther from the centre, and, as P and P move in'unison, as soon as or slightly before P leaves the grooveG, P is lifted'past the stop S. If Kmoves a step backwards F is moved in the opposite direction and the effect is reversed.

The parts indicated in Figures 4, i5 and 6, are as indicated in the key diagram, Figure 1, so that the above description-may be taken as applyingto them also.

Various modifications of the -mechan'ism for restoring the differential gear 1) to the position'of conformity maybe devised, e. g. instead of cutting the scrolls on flat discs F and F these discs may be replaced, for example, by cylinders B and B with parallel axes (Figure 7) and the pins P P fixed to the rocking arm L L by pins Q Q} fixed to a rod R capable of translation parallel to the axes of the cylinders in such a way that Q and Q} engage in suitably'fo'rm'ed grooves cut on the cylindrical faces of B and B thus the form'ofthe groove on B may consist of two straight grooves each nearly halfthe length of the cylinder and 'the grooves in the cylinderB may consistof its two ordinary helices connected by a short groove parallel to the axis of B as shown in Figure 7, this short groove taking the place of the obstruction S (Figure Thecylinders of Figure 7 instead of having coincident axes may be arranged side by side with parallel axes in which case the long rod carrying the two pins may be replaced by a short rod with the pins on opposite sides of the rod. 7

It will be recognized that the scrolls on the driven elements need not consist of grooves, for example, they may consist of ribs or other suitable equivalent, and in such cases instead of pins being provided for engagement with the scrolls equivalents suitable for the purpose may be used.

As an example of one application of this invention, the mechanism, see Figure 1, may be used for steering a ship in conformity with motions of a receiver operated by control from a gyro-compass, in which case the gyro-controlled receiver would be connected to rotate shaft K, shaft G is continu- -ously rotated by a power drive, and shaft the control mechanism comprising a second differential, the second differential comprising a first driving element driven by the third connection from the first differential, and two driven elements, one a restricted motion e1ement, the other an extensive motion element, means for causing motion from the first driving element to be imparted to one or other or momentarily to both of the control mechanism, the first differential comprising a first connection for communicating motion to its first element, a second connection for communicating motion from the servo-motor to its second element, and a third connection driven by its thirdelement, the control mechanism comprisinga second differential, the second differential comprising a first driving element driven by the third connection from the first differential, and two driven elements, one a restricted motion element having a short scroll, the other an extensive motion element having a long scroll, means moving in unison engaging with the scrolls, and a connection from the restricted motion element to the servo-motor control gear, for the purposes set forth.

ARCHIBALD BARR. WILLIAM STROUD. 

